Vagal cardiac function and arterial blood pressure stability

Wray, D. Walter; Formes, Kevin J.; Weiss, M.S.; O-Yurvati, Albert H.; Raven, Peter B.; Zhang, Rong; Shi, Xiangrong

doi:10.1152/ajpheart.2001.281.5.h1870

Cited by 54 publications

(65 citation statements)

References 26 publications

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“…MAP increased during cholinergic blockade in both supine and HUT positions. This result is consistent with previous studies [31,37] and might result from the increase in Q.…”

Section: Discussionsupporting

confidence: 94%

“…Each of these populations exhibits parasympathetic dysfunction, which is consistent with altered arterial baroreflex control of the heart [27][28][29][30][31]. In the present investigation, however, complete cardiac vagal blockade did not disturb the baroreflex control of arterial blood pressure during HUT, and arterial blood pressure was well maintained.…”

Section: Discussionsupporting

confidence: 73%

“…However, HR increases during LBNP were unchanged by vagal blockade [33], while during 40 min of 50° HUT the increase in HR required sympathetic activation [34]. In contrast, during LBNP the increases in HR mediated via vagal withdrawal have been identified using linear dynamic analysis of HR variability [31]. In the present investigation, the 25% increase in HR from the supine to the HUT position decreased to 8% after the vagal blockade (Table 1), suggesting that the HR increase during the 12 min of HUT was a result of a combination of vagal withdrawal and sympathoexcitation.…”

Section: Discussionmentioning

confidence: 99%

“…Their mean age was 27 years (range [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], height 183 cm (168-198), and weight 77 kg (57-97). All subjects provided written informed consent, which conformed to the Declaration of Helsinki and was approved by the Ethics Committee of Copenhagen (KF 01-369/97).…”

Section: Methodsmentioning

confidence: 99%

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Carotid-Cardiac Baroreflex Function Does Not Influence Blood Pressure Regulation during Head-Up Tilt in Humans

et al. 2006

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Abstract:The influence of the carotid-cardiac baroreflex on blood pressure regulation was evaluated during supine rest and 40° head-up tilt (HUT) in 9 healthy young subjects with and without full cardiac vagal blockade. The carotid baroreflex responsiveness, or maximal gain (G MAX ), was assessed from the beatto-beat changes in heart rate (HR) and mean arterial pressure (MAP) by the variable neck pressure and suction technique ranging in pressure from +40 to -80 Torr, with and without glycopyrrolate (12.0 ± 1.0 µg/kg body weight; mean ± SE). In the supine position, glycopyrrolate increased the HR to 91 ± 3 bpm, from 54 ± 3; MAP to 89 ± 2 mmHg, from 76 ± 2; and cardiac output to 6.8 ± 0.3 l·min -1 , from 4.9 ± 0.3 (P < 0.05). The G MAX of the carotid baroreflex control of HR was reduced to -0.06 ± 0.01 bpm·mmHg -1 , from -0.30 ± 0.02 (P < 0.05) with no significant effect on the G MAX of the carotid baroreflex control of MAP. During HUT the carotid baroreflex control of MAP was unchanged, though the G MAX of the carotid baroreflex control of HR was increased (P < 0.05). During HUT, central blood volume, assessed by electrical thoracic admittance, and total vascular conductance were decreased with and without glycopyrrolate. Furthermore, glycopyrrolate reduced G MAX of the carotid baroreflex control of HR during HUT (P < 0.05) with no significant effect on G MAX of the carotid baroreflex control of MAP. These data suggest that during supine rest and HUT-induced decreases in central blood volume, the carotid baroreflex control of HR is mediated primarily via parasympathetic activity. Furthermore, the maintenance of arterial blood pressure during postural stress is primarily mediated by arterial and cardiopulmonary reflex regulation of sympathetic activity and its effects on the systemic vasculature.Key words: arterial blood pressure, baroreflex, central blood volume, heart rate.The balance between the contribution of the carotid-cardiac and the carotid-vasomotor reflex arms to the carotid baroreflex (CBR) responses to changes in arterial pressure is altered during upright seating compared to the supine position [1]. This change in balance identified that the major adjustment to changes in posture primarily involved the carotid-vasomotor arm of the reflex [1]. This finding confirmed earlier work involving reflex adjustments to reductions in central blood volume (CBV) induced by lower body negative pressure (LBNP) [2]. Furthermore, in average healthy and fit young adults the maximal gains (G MAX ) of the carotid-cardiac and the carotid-vasomotor arms of the CBR were augmented during decreases in CBV [3,4] induced by head-up tilt (HUT) or LBNP [5,6].However, patients who exhibit parasympathetic dysfunction during an orthostatic challenge also exhibit decreased vasomotor responsiveness [7][8][9], indicating that a dysfunction of the carotid-vasomotor arm may be the underlying mechanism of the postural syncope despite the parasympathetic dysfunction. These findings raise the question of whether parasympathetic dysfunctio...

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“…MAP increased during cholinergic blockade in both supine and HUT positions. This result is consistent with previous studies [31,37] and might result from the increase in Q.…”

Section: Discussionsupporting

confidence: 94%

Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Carotid-Cardiac Baroreflex Function Does Not Influence Blood Pressure Regulation during Head-Up Tilt in Humans

et al. 2006

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“…Previous results have indicated a close correlation between tonographic and direct ABP measurements. [14][15][16] Each subject underwent identical assessments before and after each SGB procedure. Beat-tobeat ECG and ABP signals were digitized and collected at a rate of 500 samples/s using an online personal computer interfaced with an analog-to-digital converter (DI-720U, Dataq instruments).…”

mentioning

confidence: 99%

Effects of Bilateral Stellate Ganglion Block on Autonomic Cardiovascular Regulation

Song

Hwang

Lee

et al. 2009

Circ J

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Vagal blockade suppresses the phase I heart rate response but not the phase I cardiac output response at exercise onset in humans

et al. 2021

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Purpose We tested the vagal withdrawal concept for heart rate (HR) and cardiac output (CO) kinetics upon moderate exercise onset, by analysing the effects of vagal blockade on cardiovascular kinetics in humans. We hypothesized that, under atropine, the φ1 amplitude (A1) for HR would reduce to nil, whereas the A1 for CO would still be positive, due to the sudden increase in stroke volume (SV) at exercise onset. Methods On nine young non-smoking men, during 0–80 W exercise transients of 5-min duration on the cycle ergometer, preceded by 5-min rest, we continuously recorded HR, CO, SV and oxygen uptake ($$ \dot{V} $$ V ˙ O2) upright and supine, in control condition and after full vagal blockade with atropine. Kinetics were analysed with the double exponential model, wherein we computed the amplitudes (A) and time constants (τ) of phase 1 (φ1) and phase 2 (φ2). Results In atropine versus control, A1 for HR was strongly reduced and fell to 0 bpm in seven out of nine subjects for HR was practically suppressed by atropine in them. The A1 for CO was lower in atropine, but not reduced to nil. Thus, SV only determined A1 for CO in atropine. A2 did not differ between control and atropine. No effect on τ1 and τ2 was found. These patterns were independent of posture. Conclusion The results are fully compatible with the tested hypothesis. They provide the first direct demonstration that vagal blockade, while suppressing HR φ1, did not affect φ1 of CO.

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Vagal cardiac function and arterial blood pressure stability

Cited by 54 publications

References 26 publications

Carotid-Cardiac Baroreflex Function Does Not Influence Blood Pressure Regulation during Head-Up Tilt in Humans

Carotid-Cardiac Baroreflex Function Does Not Influence Blood Pressure Regulation during Head-Up Tilt in Humans

Effects of Bilateral Stellate Ganglion Block on Autonomic Cardiovascular Regulation

Vagal blockade suppresses the phase I heart rate response but not the phase I cardiac output response at exercise onset in humans

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